Nfld. & Labrador

Hearing research tapping into Newfoundland's 'founder' population

A hearing research lab in Grand Falls-Windsor is searching for the genetic causes of hearing loss in Newfoundland families.

Genomics-Based R&D Centre for Health is in year two of starting project

Holly Rowsell demonstrates a hearing test in the Genomics-Based R&D Centre for Health in Grand Falls-Windsor. The small facility, located in a room in the Excite Corporation building, houses multiple types of common hearing tests. If a family is selected for deeper study, they might be put through six to eight hours of testing. (Garrett Barry/CBC)

The unique genetic makeup of Newfoundland's population is offering opportunity to a team of researchers in Grand Falls-Windsor, working to find the deep causes of hearing loss.

The Genomics-Based R&D Centre for Health is taking advantage of Newfoundland's big families and long lineages, and what's called a "founder" population — the fact that a big majority of people in the province can link their family history back to England and Ireland.

The patterns become very clear, fairly quickly.- Terry Young

Terry-Lynn Young, a lead researcher at the centre, says most of the families in the province can link their heritage back to the wave of European settlement on the island in the 17th and 18th centuries — and, compared with the rest of the world, there hasn't been much immigration since.

"If you took the whole world's population, as a big jar of jellybeans, all different colours, if just a few of those jellybeans cross the Atlantic ocean, and established the Newfoundland population, that's essentially what happened," she explains. 

Terry-Lynn Young is a professor of genetics at Memorial University and a researcher. She's worked on genomics research about arrhythmogenic right ventricular cardiomyopathy, nicknamed the 'Newfoundland curse.' (Garrett Barry/CBC)

"You might have lots of blues, lots of reds, lots of yellows, but you have no pinks. So when you're looking for variants that cause disease, because we have a founder population, we have less number of variants."

Because many Newfoundland families are big, there are lots of yellows and blues for Young and her group to work with. That means lots of groups of people who carry identical gene mutation, which gives researchers ample opportunity to study whether that particular mutation is responsible for hearing loss.

We look for perfect fits.- Terry Young

"Some of our families actually had 23 and 24 brothers and sisters," Young said. "With that number of brothers and sisters … the patterns become very clear, fairly quickly."

Proof of project

The centre is now focusing on three big families, as part of a proof of project study.

Members of these big families have had their genomes sequenced, and have had in-depth hearing tests. Using high-powered computers, the research team can then search for a particular gene mutation that everyone with a particular type of hearing loss in the family has, and everyone without that hearing loss in the family does not have.

Young shows a pedigree, a type of detailed family tree with information on genetics and disease. For this particular pedigree, researchers have indicated that the mutation that gives people an 'A' is found in everyone with hearing loss. (Garrett Barry/CBC)

"We look for perfect fits," said Young. "For every family pattern we have like this, and we figure out what the gene is, it's definitive."

It's quite powerful and it's quite rewarding.- Terry Young

The hearing tests are much longer than what you'd find in a normal clinic. According to audiologist Anne Griffin, the series of tests might take six to eight hours.

"Some of them you listen, and you use a mouse, some of them you actually sit back and have some wires and you hear funny sounds," she explained. "It's all about trying to find out more about how does your hearing work."

The research team is in Year 2 of of their three-year initial project. They hope to build deep models of the particular characteristics of hearing loss linked to particular genetic mutations, in an effort to gather information that can improve hearing aids. (Garrett Barry/CBC)

Because the researchers are gathering information on a particular type of hearing loss, and its genetic causes, they aim to find out where exactly in the process hearing is breaking down.

"Presumably the same kind of issue at the same point in the pathway," said Griffin. "Or several points in the pathway, and by studying that now we really start to see a pattern. Now we really start to identify 'where is the weak spot, and what might we do about it better?'"

Bringing it public

Young says the research team wants to ensure there's a public benefit to their research.

They're aiming to have their research lead to improvements in hearing aids for patients with the type of hearing loss they've studied.

Jill Lowther, an audiologist and research assistant in the Grand Falls-Windsor lab, points towards a test result measuring the functioning of her cochlea in a test subject. The chart of the red graphed line shows the health of the cochlea at different frequencies. (Garrett Barry/CBC)

The families who've been studied by the centre are already seeing benefits, according to Griffin, by learning more about their genome and their hearing. There's also opportunity for other families, or family members, to benefit from the genomic approach that their research is helping to advance.

She says the gene sequencing can give families a good idea of who is likely to develop hearing loss, and that's a tool that's especially useful for hearing loss that develops later in life.

"It allows for a proactive identification of risk, and then, because of that, it allows an opportunity to manage better," she said. "So you now know, OK, certain children should probably be having a standard hearing test every year every two years until they are 20."

"We know who in the family needs to be followed and who doesn't," said Young. 

"It's quite powerful and it's quite rewarding." 

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About the Author

Garrett Barry

Journalist

Garrett Barry is a CBC reporter based in Gander.